Sunlight, Sexuality, and Mental Health

The association of sunlight and mental and sexual health has long traditions. The summer solstice is historically linked with fertility and sexuality by cultures everywhere. June is the most popular wedding month. There used to be ceremonies symbolic of marriage at midsummer. Traditionally in spring, a young man proposed to a girl requesting she be his wife. Marriages were usually in midsummer. The couple dressed up accompanied by adults and children came to the church. Afterward in most local traditions there was feasting, drinking, and dancing into the evening. They were actually performing an ancient magical rite emphasizing the connection between sexuality and fertility in humans.

Numerous studies indicate that fertility and sex drive increase when sunlight is more intense. Testosterone levels in males are higher in the summer. Studies at Boston State Hospital by Dr. Abraham Myerson found that ultraviolet light increased male hormone levels by 120%. Ultraviolet light also increases the level of female hormones. More children are born during the spring and more birth control devices are purchased during the summer months.

A further link between sunlight, sex drive and health is the findings that women who have frequent orgasms (with or without a partner) are much more likely to survive breast cancer. Since survival from breast cancer depends largely on whether the cancer has metastasized to other parts of the body, it looks like orgasms somehow prevent metastasis, probably by immune-system stimulation.

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On the other hand, sex drive wanes in winter. A decrease in female fertility in winter has been documented beginning with North Pole explorer Admiral Byrd's observations a century ago. His expedition reported that Eskimo women lacked menstruation, and thus ovulation, during the periods of 24 hour darkness in their winter. Also in winter, male testosterone levels drop and sperm counts are lower.

Infertility is a problem that seems to have increased in recent years. Research on light therapy has suggested that our decreased exposure to natural sunlight reduces fertility. The average office lighting is a much lower intensity than sunlight and lack the full spectrum of sunlight.

Light was first used to help infertile couples by Dr. Edmond Dewan at the renowned John Rock Reproductive Clinic in Boston1. Couples were given a specially designed light to keep on while they were asleep for three nights a month. The three nights were planned to be the same three days over which ovulation was expected to take place. The couples using the light therapy had a much higher rate of conception than those not using the light.

Seasonal Affective Disorder (SAD)

An estimated 35 million Americans suffer from SAD for whom sunlight or full spectrum light therapy from November to April often improves their mental state. SAD symptoms include: limiting social contact, loss of energy, depression, decreased interest in sex, weight gain, oversleeping and withdrawal. This usually occurs in the winter.

SAD has been successfully treated with exposure to bright artificial light of higher intensity than is usually found in the home or in the work place. Many people not suffering from SAD may nonetheless have seasonal changes which could be helped by environmental light supplementation.

Six patients with Seasonal Affective Disorder showed marked improvements in depressive symptoms after following three different two-hour schedules of bright artificial light, and they relapsed when the light was withdrawn.

Bright light can suppress nighttime melatonin production in humans, but ordinary indoor light does not have this effect. This finding suggested that bright light may have other chronobiologic effects on humans as well. Eight patients who regularly became depressed in the winter (as day length shortens) significantly improved after one week of exposure to bright light in the morning (but not after one week of bright light in the evening). The antidepressant response to morning light was accompanied by an advance (shift to an earlier time) in the onset of nighttime melatonin production. These results suggest that timing may be critical for the antidepressant effects of bright light.

Sunlight, the Pineal Gland, and the Sleep-waking Cycle

Sunlight synchronizes the circadian sleep-wake cycle by the pineal gland. The French philosopher Descartes decided that the pineal gland was the seat of the human soul, the location of what we call the mind. The pineal does contain a complete map of the visual field of the eyes, and it plays several significant roles in human functioning.

The pineal gland receives information from the eyes to regulate timekeeping for the human body. At night it secretes melatonin which, in turn, induces sleep. Melatonin has been shown to inhibit the growth and metastasis of some tumors in experimental animals, and may therefore play a role in cancer inhibition. Removal of the pineal gland and/or reduction in melatonin output have been implicated in the increased incidence of breast cancer in laboratory animals. Patients who have breast cancer have lower levels of melatonin in the blood. The hormone has also been shown to be protective against genetic damage, and it has a stimulatory effect on the immune system.

Sunlight Exposure may Reduce Schizophrenia in Newborns

Schizophrenia, in Europe and North America is most common in persons born in March. People with darker skin pigments who migrate to northern countries are 3 to 4 times more likely to develop schizophrenia than lighter-pigmented inhabitants of these countries. Drs. John McGrath and Alan Mackey-Sim (Centre for Schizophrenia Research, Wacol, Australia and Griffin University, Brisbane, Australia) presented evidence that a lack of enough sunlight to form adequate vitamin D in pregnant mothers causes this increase in of schizophrenia. Sunlight normally converts a molecule, 7-dehydrocholesterol, into vitamin D. Vitamin D in turn increases the production of nerve growth factor that is needed in the developing brain of a child.

Further studies found that pregnant rats, that were vitamin D deprived, produced offspring with brain abnormalities and behavior abnormalities similar to those observed in humans with schizophrenia or a type of rat bred to act as a model of the disease. Dr. McGrath comments that a few minutes of standing in sunlight every day might be enough to protect a developing fetus from the disease.